Small Intestine and Colon Flashcards

Question

How do conditions of malabsorption typically present?

Answer 1

General malabsorptions: - diarrhea, particularly **steatorrhea** - **weight loss** (if chronic) - distension - flatulence - associated deficiencies Specific malabsorptions: -**varies**, dependent on what is not absorbed or associated deficiency

Answer 2

genetic defect in Cl ion transporter, **CFTR**, found in **exocrine glands** as well as **respiratory, GI**, and reproductive **epithelium -\>** imparied water transport and **thickened secretions**

Answer 3

_Failed intraluminal digestion_: - pancreatic duct obstruction due to thickend secretions -\> pancreatitis/**exocrine pancreatic insufficiency** -\> **carbs, lipids, and proteins not digested** - general malabsorption due to lack of digestive enzymes -\> **steatorrhea** and **malnutrition** - **impaired water secretion** into GI lumen -\> **viscid mucous** -\> **obstruction**

Answer 4

gluten-sensitive, immune-mediated enteropathy: - **autoimmune** reaction triggered by **gluten** leading to damage of **intestinal epithelium** - gliadin trigger epithelial cells to release IL-15 -\> activates CD8+ T cells expressing NKG2D - NKG2D binds **MIC-A** expressed on **stressed enterocytes** -\> cell-mediated **damage of epithelium** -\> malabsorption - gliadin also binds **HLA-DQ2** and **HLA-DQ8** on APCs -\> activate CD4+ T cells -\> activate B cells -\> production of **anti-gliadin**, **anit-tTG**, and **anti-endomysial** abs

Answer 5

Lab: - **anti-tTG IgA** (gold standard) - anti-endomysial IgA - both high sens. and spec. Histo: - **villous atrophy** (loss of villi) - **crypt hyperplasia** (elogation of crypts - increased **intraepithelial CD8+ T cells** - none are unique to celiac disease

Answer 6

**Bimodal** Children: - onset with **introduciton of wheat** products to diet **~6-24 months** - **M=F** Adults: - **30-40** - **F**\>M

Answer 7

Classical: - chronic **diarrhea** - **bloating/cramping** - **malabsorption** -\> iron/vitamin deficiency -\> **anemia** -\> -chronic **fatigue**

Answer 8

_dermatitis herpatiformis_: -autoimmune blistering disease **associated with anti-tTG** produced in celiac disease

Answer 9

Often onsets at young age and pt may not be able to describe symptoms. GI: - **chronic diarrhea/steatorrhea** - abdominal **distension/pain** -\> **irritability** - **malabsorption** -\> **failure to thrive/weight loss** Extraintestinal (_impact of malabsorption on growth_): - **arthritis** - growth restriction -\> **short** - **delayed puberty**

Answer 10

**Most cases are atypical** in their presentation, delaying testing for celiac disease **many cases are asymptomatic** and go undetected

Answer 11

No treatment available -\> **gluten-free diet** to prevent symptoms

Answer 12

_Environmental sprue/non-tropical sprue_ **similar to celiac disease** (which is alternatively called non-tropical sprue) in presentation/appearance but: **-cause is unknown** - associated with **poor sanitation/hygiene** -\> responds to antibiotics - endemic to the **tropics** (\*\*\*_visiting or from there_\*\*\*) Presentation: - chronic **diarrhea/steatorrhea** - **bloating/cramping** - **malabsorption** -\> iron/vitamin deficiency -\> **anemia** -\> chronic **fatigue** Biopsy: **-villous atrophy** **-cryptic hyperplasia**

Answer 13

antibiotics

Answer 14

- **celiac** predominates in the **duodenum**; **environmental** predominates in the **ileum and jejunum** (B12/folate deficiency) - environmetal responds to Abx - environmental is typically preceeded by infectious diarrhea

Answer 15

**IPEX** - **_I_**mmune dysregulation, **_P_**olyendocrinopathy, ****_E_**nteropathy**, _X_-linked - **X-linked** autoimmune disorder associated with mutation in **FOXP3** -\> **loss of T_reg cells** - presents early in life Presentation: - eczema - T1DM - malabsorption -\> **chronic diarrhea** -\> **failure to thrive**

Answer 16

- anti-enterocyte - anti-goblet cell - anti-parietal cell - anti-islet cell (-\> T1DM)

Answer 17

immune supression: -cyclosporine

Answer 18

Lactase: **brush-border enzyme**, breaks down lactose -\> galactose and glucose -when deficient, **lactose remains in lumen** and **exerts osmotic force**, pulling water into stool -\> **osmotic diarrhea**

Answer 19

_Congenital_: - _mutation_ in lactase gene - **very rare** Acquired: - _downregulation_ of lactase gene - common in Native American, Africian American, and Chinese - can be **acquired following gastroeneteritis** and **gradually improve over time**

Answer 20

_Following consumption of milk_: - **watery, frothy** **diarrhea** (osmotic) - **cramping** - **flatulence** Symptoms are **more variable in aquired** due to variance in active lactase

Answer 21

autosomal recessive disorder associated with microsomal triglyceride transfer protein, **MTP** - blood has no **lipoprotein B** - body is unable to transport fats and fat soluble vitamins from the intestine - **diarrhea/steatorrhea** - **failure to thrive** - **lipid accumulation in enterocytes** - membrane defects -\> **acanthocytes/spur RBCs**

Answer 22

_Irritable bowel syndrome_: **chronic, relapsing**: - **abdominal pain** - **bloating** - **change in bowel habits** It has no known cause: - diagnosed using **Rome criteria** - diagnosed by **elimination** of DDx's

Answer 23

**NONE**; GI tract has a **normal macroscopic and microscopic** appearance

Answer 24

- **women** - **20-40** years

Answer 25

**blind ending segment** of colon resulting from **surgery that produced an ostomy**

Answer 26

**Normal gross appearing** colon but with **microscopic abnormalities** Symptoms: -**chronic diarrhea** (non-bloody) - **weight loss** - **abdominal pain** _Collagenous colitis_: increased **subepithelial collagen** _Lymphcytic colitis_: **intraepithelial lymphocyte infiltrate**; commonly in setting of _celiac dz or autoimmune dz_

Answer 27

SI and colon _involved in most cases of GVHD_ - **watery diarrhea** - **apoptosis** of **crypt cells**

Answer 28

false divertiucla/outpouchings of the mucosa and submucosa of the colon through discontinuities in the muscular layer

Answer 29

Epi: - rare \<30 - prevalence increases with age -\> 50% by age 60 - _more common_ in **Western** countries (**left-sided** diverticula) - less common in **Asia and Africa** (**right sided** diverticula)

Answer 30

**_most are asymptomatic_** Those that are symptomatic (20%): - **painless lower GI bleed/hematochezia** - **lower abdominal pain/cramping** - **constipation** - **sensation** of **not being able to empty the rectum**

Answer 31

inflammation of diverticula Complicaitons: - **abscess** - **fistula** formation - **perforation**

Answer 32

**colo-rectal**, but can be found throughout GI tract

Answer 33

**Sessile** polyps: -small **elevations of mucosa w/o stalks** **Pedunculated** polyps: - **protrusions of mucosa w/ stalks** - typcially preceded by a sessile precursor

Answer 34

- **hyperplastic** - **inflammatory** - **hamartomatous**

Answer 35

Benign epithelial proliferation: - **decreased epithelial turnover** and decreased sheding leading to **"piling up" of** **NORMAL cells** (no dysplasia) - small (\<5 cm) **sessile polyp** **-serrated** crypts -**tufting** of surface due to crowding **-left/descending colon**

Answer 36

very similar in presentation to **_serrated, sessile_ adenoma** which is malignant, and **must be ruled out**

Answer 37

Benign polyp: - caused by **repeated injury and healing** of the mucosa - typcially assocaiated with **solitary rectal ulcer sundrome (SRUS)** where anorectal sphincter fails to relax -\> recurrent abrasion/ulceration Appearance: - **mixed _inflammatory_ infiltrates** - erosion - **epithelial hyperplasia w/ fibromuscular hyperplasia**

Answer 38

disorganized growth of mature cells native to local tissue - **autosomal dominant inheritance** (if genetic etiology) - involved genes tend to be **tumor supressors or protooncogenes** -\> increased risk of malignancy - the _polyps themselves tend to be benign_

Answer 39

- **juvenile polyposis syndrome** - **Peutz-Jeghers syndrome** - Cowden syndrome - Cronkhite-Canada syndrome

Answer 40

_Autosomal dominant syndrome_ (SMAD4) - presents **\<5 years** - **\>10 polyps** (mostly **colon**, can involve _stomach and SI_) - high risk of bleeding -\> **rectal bleeding** -\> **anemia** - risk of **intussusception** and **obstruction** Increased risk of **gastric, SI, and colon adenocarcinoma**

Answer 41

_Autosomal dominant syndrome_ (STK11): - mucocutaneous hyperpigmentation, especially **oral** (**mucosal "freckles"**) - **arborizing** polyps (most commonly **SI**, can occur in _colon, stomach, bladder and lungs_) - can cause **intussusception** Increased risk of **colorectal, breast, lung, and pancreatic cancer**

Answer 42

**pre-malignant** lessions that have a **high risk becoming adneocarcinomas** -typcially distinguished from other, more benign polyps by the **pressence of a stalk and dysplasia**

Answer 43

Sessile serrated adenomas: - still a **pre-malingnant lesion** - **lack a stalk** -\> sessile - **lack dysplasia** -\> hyperplastic Very **similar in appearance to benign hyperplastic polyps**, but can become malignant: - _crypts are serrated to their base_; more common in _right_ colon (adenoma) - crypts are only serrated partway down; more common in left colon (hyperplastic)

Answer 44

**size**: - \<1cm -\> minimal risk - \>4cm -\> 40%

Answer 45

Classic, adenoma-carncinoma sequence: - associated with **FAP or sporadic** mutations in **APC/WNT** pathway (_growth supression_) (APC-\> K-RAS -\> P53) - 70-80% of sporadic CRC - **polypoid precursor** -\> _non-mucinous_ **adneocarcinoma** - typcially **left-sided** (**sporadic only**; FAP has no preference) MMR sequence: - associated with **NHPCC or sporadic** mutations in **mismatch repair pathway** (**MLH1/MSH2**) - 10-15% of sporadic CRC - most common inherited CRC (HNPCC) - non-polypoid, **serrated sessile precursor** -\> _mucinous_ **adneocarcinoma** - typcially **right-sided**

Answer 46

**Aspirin/NSAIDs** -**increased COX expression** is part of transformation so COX inhibitors impede progression

Answer 47

autosomal dominant syndrome: - **development of \>100**, potentially 1000's of **adenomatous polyps** - mutation in **_A_**denomatous **_P_**olyposis **_C_**oli (**APC**) gene - associated with **congenital retinal pigmented epithelium hypertrophy** (can be deceted at birth) **100% risk** of developing adenocarcinoma **by age 45**

Answer 48

Very **similar to FAP** but is **more mild** (\<100 polyps) and **slower progression** (CRC around 50 y/o) -**MYH** gene is affected instead of APC

Answer 49

-prophylactic **proctocolectomy** w/ **ileoanal anastamosis** (prior to age of 20) otherwise colorectal cancer is inevitable

Answer 50

**variant of FAP** (APC mutation): -additional risk of **osteoma and soft tissue tumors**

Answer 51

variant of FAP (APC mutation): -additional risk of **brain tumors**

Answer 52

Hereitary _nonpolyposis_ colorectal cancer (HNPCC): - **autosomal dominant** mutations in **mismatch repair genes** (**MSH2/MLH1**) - **atypical adenomas** (**sessile** instead of pedunculated) with high rate of prgression to CRC - _most common inherited_ cause of CRC

Answer 53

- **colon** (HNPCC) - **endometrium** - **stomach** - **ovary**

Answer 54

_Right-sided/proximal_: - flat, exophytic masses; "**inverted mushroom**" - **LIGB -\> anemia** - rarely casue obstruction _Left-sided/distal_: - annular, "**napkin-ring**" constrictions - **blood streaked stools** - **change in bowel habits** - may lead to **obstruction**

Answer 55

- LNs - liver

Answer 56

- **depth** of invasion - **metastasis to LNs** less important but still prognostic: - mucinous (MMR/sessile serrated) - poorly differentiated

Answer 57

- fatigue/weakness from **IDA** in **older men** or **postmenopausal women** (anemia of unknown origin) - **GI bleed** - most common presenting complaint in colon cancer and frequent with others

Answer 58

most found in **jejunum/ileum** (most common site of carcinoid tumors in whole GI tract) Secrete **serotonin** - serotonin is mostly release into **portal circulation** -\> metabolisim in liver (**first-pass effect**) - if high tumor burden or directly secreted into **systemic circulation** -\> **carcinoid syndrome** **Cacinoid syndrome:** - _flushing, sweating_ - bronchospasm - colicky abdominal pain, diarrhea - _right-sided_ cardiac valve fibrosis_{(pulmonary system metabolizes 5HT preventing it from reaching L heart)}

Answer 59

***Streptococcus gallolyticus/bovis*** endocarditis

Answer 60

**CEA** - not reliable in screening as it is not always present - can be used to monitor CRC known to produce CEA or similarly look for relapse

Answer 61

APC (chromosome 5) **_A_**denomatous **_P_**olyposis **_C_**oli gene

Answer 62

APC -\> β-catenin -\> K-RAS -\> TP53, DCC, COX-2

Answer 63

MLH1, MSH2

Small Intestine and Colon Flashcards

(89 cards)